Abstract:
This study deals with the design and fabrication of a single-phase
voltage stabilizer using 8051 microcontroller. The basic building blocks for
this design include an AT89S51 microcontroller, a solid-state relay (SSR), a
stabilizer transformer, a diode-based bridge rectifier, a 7805 regulator, an
ADC 0804 and LEDs to display the digital value of the input voltage. This
design is based on the principle of varying the input voltage to obtain an
output voltage that is considerably constant. Any time there is a change in the
input mains supply voltage, a corresponding voltage is digitised and fed into
the microcontroller which then switches on an appropriate SSR to add or
subtract a winding to or from the transformer, so as to maintain the output
voltage. Apart from the voltage stabilisation, the device also provides voltage
protection against transient voltages that are harmful to industrial, laboratory
and domestic appliances. The voltage differences from red, yellow and green
windings were however higher. The sudden change in AC voltage was due to
only two additional windings. As a result, three relays were used to select the
output voltages as the input voltage changes. This situation can be avoided
when a transformer with more windings (tappings) are used. A variable
transformer was used to vary the AC input voltage from 270 V AC and the
corresponding voltages on the ADC output and the AC outputs from the Red,
Yellow and Green tappings of the transformer were recorded.
